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"Black Mass" stars Johnny Depp and Dakota Johnson didn't disappoint fans who had waited hours outside the Coolidge Corner Theater in Brookline, Massachusetts, Tuesday night for the chance to see the local film's famous actors up close.

On the red carpet, Depp said he did a lot of research to ensure he portrayed South Boston's notorious mob boss James "Whitey" Bulger accurately.

"Families of the victims say he was pure evil, I just don't think that exists," Depp began.

To that end, Depp says he reached out to the now elderly ex-gangster in prison.

"I tried to contact Mr. Bulger through his attorney Jay Carney and about a week later, I got a response that said that Jimmy respectfully declines, based on the fact that it's a film that stems from a book that he's not- let's say- most enthusiastic about," Depp explained.

Johnson says she had a special connection to the film years before she was selected to play the role of Bulger's girlfriend and the mother of his only son Lindsey Cyr.

"When he was arrested in Santa Monica, I went to high school in Santa Monica so I found out about it then. Obviously it was on the news and I did a lot of reading and research and it was very fascinating and that was years prior to even making this project," Johnson said.

The film's producer and director, in addition to many of its local stars, felt a certain responsibility to be sensitive to he victims' relatives but not sugar coat what Bulger had done.

'Black Mass' Trailer

"I know we were trying to be as respectful and not make Whitey, not glamorize him or say that this is cool what he did, when you see the movie he doesn't come out of it very well," Medford native Julianne Nicholson said. She plays John Connolly's wife, Marianne, in the film.

"When I decided to make the film, that was the most important thing that I or any of the cast had to consider, because so many people were affected by these men and their exploits and certainly the city of Boston itself has an emotional wound that has yet to heal," Scott Cooper, the director and producer said.

The movie is based on a book of the same name by former Boston Globe reporters Dick Lehr and Gerard O'Neill. It chronicles Bulger's rise to become the city's most feared gangster, ruling its underworld from the 1970s into the 1990s while working with the FBI as an informant on the New England Mafia, his gang's main rival.

Bulger fled Boston in 1994 after being tipped off by his FBI handler that he was about to be indicted. He lived as fugitive for more than 16 years before he was captured in Santa Monica, California, in 2011.

Bulger, 86, was convicted in 2013 of playing a role in 11 killings and multiple other crimes. He is serving a life sentence in federal prison.

While Whitey Bulger rose to become one of the city's most powerful criminals, his brother, William, became one of the state's most powerful politicians, serving as president of the state Senate from 1978 until 1996.

William Bulger, who's played by Benedict Cumberbatch in the film, told the Boston Herald that he's not much of a moviegoer but will likely see "Black Mass" eventually. He said he hasn't seen the trailers or read the book and doesn't know too much about the movie's stars.

William Bulger, who has not said much publicly about his brother, says he and Whitey are in touch.

"Black Mass" made its world premiere at the Venice Film Festival and was screened at the Toronto International Film Festival last week.